1. Field of the invention
The present invention is related to a durable pivotal connecting device for a table lamp between the base and the supporting post of the lamp. The present invention is especially related to a pivotal connecting device taking advantage of the elastic nature of a plurality of bendable spring leaves in assembling an adjusting bolt, a transverse bar and two connecting rods in a linking mode, thereby, frictional resistance at the contact area between a rotation seat and the spring leaves can be controlled to tightly bind and fix or release the rotation seat for the supporting post to get a function of adjustment in rotation angle.
2. Description of the Prior Art
A conventional table lamp seen in the markets is provided on one end of the supporting post with a lampshade and a lamp pipe, while the other end thereof is pivotally mounted on the base of the lamp set, these form the main part of the table lamp. However, no matter the base of the lamp set is placed on or is clamped on a table, there is normally a pivotal connecting structure between the base and the supporting post for such purpose as that the supporting post can be rotationally adjusted for an ideal angle of illumination of the light toward the table. While pivotal connecting structures between bases and supporting posts on the table lamps seen in the markets mostly use the mode of connection with screws and nuts for assembling to have the main and subordinate rotating axles locked in positions in a given looseness of mating, and a conventional effect of adjusting the supporting posts relative to the bases can be obtained. However, the conventional pivotal connecting structures are not durable, the supporting posts are frequently adjusted directly with hands, and the axle pipes of the pivotal connecting structures are assembled and controlled for their tightness of binding with screws and nuts; thereby, pivotal connecting of the supporting posts on the bases will become loose after a long period of use with frequent adjusting, and are unable to get fixed positions with enough frictional resistance any more. Although users can use tools such as screw drivers to adjust the screws and nuts on the loosened pivotal connecting structures to recover suitable tightness of binding of the supporting posts against the bases, it is surely known that, adjustment of tightness of binding between the main and subordinate rotating axles taking advantage of their threads can not afford frictional resistance required in continuous rotational adjustment of the lamp set supporting posts. The pivotal connecting structures certainly will get loose again and again; this shows that durability of the conventional pivotal connecting structures is inferior.